The Swiss-built Mirage IIIS is a licensed version of the French Mirage IIIC. Switzerland produced 36 examples of the type at the F+W state factory in Emmen. Substantial differences from French-built versions include the Hughes TARAN-18 avionics system, giving the aircraft the capability to carry the Hughes AIM-4 Falcon AAM. Mirage IIIS' also had a vast majority of their structural components strengthen for use in the rugged Swiss operating environment. Political scandal and cost overruns surrounded the Mirage IIIS program in Switzerland, with the mane "Mirage Affair".

In the 1990's, the Mirage IIIS underwent an avionics upgrade and modernization program. Upgraded Mirages can be discerned by their new, fixed canards and low-visibility gray color scheme. Switzerland retired their Mirage IIIS fleet in 1999, with the Mirage IIIRS following in 2002.